1. Field of the Invention
This invention relates to a pressure compensated shear seal solenoid valve used in subsea hydraulic control systems for operating valves, blowout preventers and hydraulically actuated wellhead connectors. Such devices require pressurized hydraulic fluid, typically operated at 1500 or 3000 psi, for their operation. The solenoid valve of the present invention is used in the control of the flow of such pressurized hydraulic fluid.
These subsea hydraulic control systems typically consist of a group of accumulator bottles in which the pressurized hydraulic control fluid is stored, a control unit for operating the aforementioned solenoid valves, and high pressure lines or hoses to carry the hydraulic control fluid from the accumulator bottles to the control unit and its solenoid valves and thence to the function, such as open or close, of the designated valve, blowout preventer or wellhead connector. The pressurized hydraulic control fluid is stored in the accumulator bottles at the desired operating pressure of 1500 or 3000 psi.
Previous designs in the industry have suffered from such deficiencies as inadequate flow rates, unreliable operation, difficulty to service or repair and being too large which causes difficulties in fitting the required number of valves in the allowable space. It is therefore desirable to have a solenoid valve that offers improved flow rates over existing designs, ease of serviceability and reduced size for ease in designing hydraulic control systems. The pressure compensated shear seal solenoid valve of the present invention offers a substantial improvement by offering a solenoid valve that yields a substantially improved flow rate, ease of serviceability and reduced size.
2. Description of Related Art
U.S. Pat. No. 4,337,829 to V. Banzoli et al. shows a control system for subsea wellheads that comprises an electronic command and control unit, a valve actuating hydraulic electric unit, a power generator unit and interconnection devices for interconnecting the hydraulic lines for controlling the system from the surface.
A subsea control module is disclosed in U.S. Pat. No. 6,161,618 to W. C. Parks et al. The subsea control module consists of a lower portion with plate for carrying hydraulic couplings and hydraulic passages from valves to couplings, a one atmosphere dry nitrogen purged chamber in a pressure vessel dome contains electronics, wiring and solenoid valves and a mandrel for extending below for engagement with a central locking mechanism in a receiver baseplate.
U.S. Pat. No. 6,318,408 B1 to Y. Fukano et al. shows a directional control valve.
A method and apparatus hydraulic and electro-hydraulic control of subsea blowout preventer systems is disclosed in U.S. Pat. No. 6,484,806 B2 to M. Childers et al.